package com.zs.itking.viewpagedialog;

import android.annotation.SuppressLint;
import android.util.Log;
import android.view.View;

import androidx.viewpager.widget.ViewPager;

public class ZoomOutPageTransformer implements ViewPager.PageTransformer
{  
    private static final float MIN_SCALE = 0.85f;  
    private static final float MIN_ALPHA = 0.5f;  
  
    @SuppressLint("NewApi")
    public void transformPage(View view, float position)
    {  
        int pageWidth = view.getWidth();  
        int pageHeight = view.getHeight();  
  
        Log.e("TAG", view + " , " + position + "");
  
        if (position < -1)  
        { // [-Infinity,-1)  
            // This page is way off-screen to the left.  
            view.setAlpha(0);  
  
        } else if (position <= 1) //a页滑动至b页 ； a页从 0.0 -1 ；b页从1 ~ 0.0  
        { // [-1,1]  
            // Modify the default slide transition to shrink the page as well  
            float scaleFactor = Math.max(MIN_SCALE, 1 - Math.abs(position));  
            float vertMargin = pageHeight * (1 - scaleFactor) / 2;  
            float horzMargin = pageWidth * (1 - scaleFactor) / 2;  
            if (position < 0)  
            {  
                view.setTranslationX(horzMargin - vertMargin / 2);  
            } else  
            {  
                view.setTranslationX(-horzMargin + vertMargin / 2);  
            }  
  
            // Scale the page down (between MIN_SCALE and 1)  
            view.setScaleX(scaleFactor);  
            view.setScaleY(scaleFactor);  
  
            // Fade the page relative to its size.  
            view.setAlpha(MIN_ALPHA + (scaleFactor - MIN_SCALE)  
                    / (1 - MIN_SCALE) * (1 - MIN_ALPHA));  
  
        } else  
        { // (1,+Infinity]  
            // This page is way off-screen to the right.  
            view.setAlpha(0);  
        }  
    }  
}